What would "you" say the pros and cons of each are?
HD7970 Pros:
Overclocks Higher
Higher software voltage allowance
Clock for clock faster then the 680/670
3 GB memory
Core Clocks don't down clock @ 70c
Cool Temps ( 65c Load single card )
Better compute performance
Scales better in Xfire
Zero core technology
Eyefinity
PCIe 3.0 Support cross the board
Will reach clocks of 1300Mhz or higher regularly.
HD7970 Cons:
Price
Bracket around physical GPU causes hard to find aftermarket cooling that is compatible.
Annoying to overclock in multi GPU configs you need to "ENABLEULPS"
Voltage capped @ 1.3v
AMD HD3D is horrible and hard to enable
I believe Drivers are holding back it's performance(Not saying there are stuttering issues or anything like that)
Comes underclocked. (Example new HD 7970 1ghz edition) This card should be clocked higher from the get go.
Fan louder
GTX 680 Pros:
Faster then the HD 7970 stock vs stock (Reference vs Reference)
Will get higher overclock then GTX 670
Core down clocking when not needed for performance is great.
Core will also automatically overclock (Even on reference card) if performance is needed.
Nvidia 3D SUrround
Cool temps @ Stock with 85% fan (58c to 60c load single card)
Doesn't need much voltage to overclock well.
Easy to find aftermarket cooling
Responds great to Anti-Aliasing
Smaller physical foot print the HD 7970
Uses less power the HD 7970 at load.
If water cooled Temps are extremely low.
GTX 680 Cons:
Low stock anywhere
Will down clock itself @ 70c on air cooling (Even if power limiter is up all the way) This causes higher sustainable clocks to be harder to maintain on while air cooling.
No way to turn off the offset clocks
Voltage locked @ 1.175v (Software) ....This card would overclock much higher if allowed more voltage.
Fan locked @ 85%
5 phase was crippled before release to 4 Phase on (reference models)
Most will not reach Core clocks of 1250Mhz (1300 Mhz is a gem card)
PCIe 3.0 not enabled on X79 boards (Have not tested since 301.42 Driver release)
SLI not scaling as well as Crossfire
Price
GTX 670 Pros:
Price
Faster then the HD 7970 stock vs stock (Reference vs Reference) in benchmarks and certain games.
Core down clocking when not needed for performance is great.
Core will also automatically overclock (Even on reference card) if performance is needed.
Nvidia 3D SUrround
Cool temps @ Stock with 85% fan (58c to 60c load single card)
Doesn't need much voltage to overclock well.
Easy to find aftermarket cooling
Responds great to Anti-Aliasing
Smaller physical foot print the HD 7970 and GTX 680
Uses less power the HD 7970 at load.
GTX 670 Cons:
Low stock anywhere (But better then GTX 680)
Locked cores not full GK104 chip
Is not guaranteed to reach clocks as fast as HD 7970 or GTX 680
Will down clock itself @ 70c on air cooling (Even if power limiter is up all the way) This causes higher sustainable clocks to be harder to maintain on while air cooling.
No way to turn off the offset clocks
Voltage locked @ 1.175v (Software)....This card would overclock much higher if allowed more voltage.
Fan locked @ 85%
5 phase was crippled before release to 4 Phase on (reference models)
Most will not reach Core clocks of 1250Mhz (1300 Mhz is a gem card)
PCIe 3.0 not enabled on X79 boards (Have not tested since 301.42 Driver release)
SLI not scaling as well as Crossfire
As you can see IMO they are pretty evenly matched. I am not showing favoritism for either card. I own 2 GTX 680's currently and I love them! I am not giving them up right now for the world! But the places where the HD 7970 excels you won't notice the difference. The place where the GTX 680/670 excels you won't notice the difference.
The only areas you will notice a difference is in specialized fields.... like folding or benchmarking. Or if battlefield 3 is your favorite game. Even then in all of these examples.... it will be very minimal. Especially in the real world. I say you will be happy Any way you go. There is no loosing in your choice my friend. If you go Nvidia... then you will be happy. If you go AMD you will be happy. I just wanted to bring this out.... so there were no misconceptions.